As is well known, a forage harvester is a vehicle that gathers crop, chops it into forage and discharges forage through a spout into a container of a vehicle, such as a tractor or a truck, which is driven alongside the harvester. In a forage harvester, it is of great importance for the driver to be able to monitor that the forage discharged from the spout is being correctly dropped into the container that is being driven alongside.
In order to appreciate the problems overcome by the invention, it is necessary first to realize that the tip of the spout may be some five meters (approximately 16.5 feet) above ground level, and more than a meter (approximately 3.28 feet) above the driver's eye level. The improved visibility that is needed is not therefore only in azimuth but also in elevation.
One way of increasing vertical visibility would be to raise the height of the roof of the forage harvester. This, however, is not possible in practice because limits are imposed on the height of the vehicle to enable it to operate on normal roads and to avoid contact with overhead obstructions such as bridges and power cables.
Another possibility would be to make the cab narrower in order to bring the door nearer to the driver and minimize the obstruction to visibility presented by the roof. However, that would restrict the space within the cab and it would not be possible to accommodate the driver's seat, a passenger seat, and the control console.
A still further possibility would be to provide a window above the side door, but such a window would not be cleaned by the windshield wiper that is normally mounted on the door and would become useless within a very short time of operation in the field.
Accordingly, there is a need for an invention that improves visibility in order to allow the spout to be seen by the driver while sitting in his normal position, i.e. without having to bend down to peer through the top of the cab door.